Deforestation and Benthic Indicators: How Much Vegetation Cover Is Needed to Sustain Healthy Andean Streams?

Iñiguez–Armijos, Carlos; Leiva, A.; Frede, Hans‐Georg; Hampel, Henrietta; Breuer, Lutz

doi:10.1371/journal.pone.0105869

Cited by 56 publications

(63 citation statements)

References 54 publications

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“…Future research should also explore management strategies, for example the maintenance of natural vegetation along riparian corridors. Recent studies from Neotropical streams indicate that riparian buffer strips can mitigate impacts of catchment land use on invertebrate assemblages (Iñiguez‐Armijos et al., ; Lorion & Kennedy, ) and stream ecosystem functioning (Silva‐Junior et al., 2014), adding to the large literature on this topic derived from temperate systems (Sweeney & Newbold, ). Although Uganda has a national policy stating that a riparian “protected zone” (with restricted agricultural activities) of at least 30 m should be kept along all rivers to protect their ecological integrity (Government of Uganda, ), this policy is not commonly enforced in agricultural areas around Kibale (V. Fugère & L. Chapman, unpublished observations).…”

Section: Discussionmentioning

confidence: 99%

Ecosystem structure and function of afrotropical streams with contrasting land use

et al. 2018

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Land use changes can strongly influence stream ecosystems, yet these effects remain poorly documented in many hotspots of deforestation such as tropical Africa. The few studies conducted in this region have mostly focused on structural aspects of stream integrity; sparse data are available for key ecosystem processes such as ecosystem metabolism and litter decomposition. To address this knowledge gap, we measured multiple ecosystem functions in rainforest and nearby agricultural (farm) streams located in an afrotropical deforestation hotspot. In two farm and forest stream pairs, we quantified the standing stock biomass of basal resources and invertebrate functional feeding groups, measured rates of litter decomposition (microbial and shredder‐mediated) and modelled invertebrate secondary production. We also calculated whole‐stream metabolic parameters over multiple weeks. To test the regional generality of our results, we then reanalysed a published dataset and assessed the functional composition of invertebrate communities from many local streams. We found that farm streams had greater algal standing stocks, gross primary production (GPP) and production‐to‐respiration ratios than forest streams, although they remained strongly heterotrophic with relatively low GPP values. Agricultural land use also led to the almost complete extirpation of invertebrate shredders, resulting in much slower litter decomposition rates at farm than forest sites despite comparable rates of microbial decomposition. Finally, farm streams had lower invertebrate biomass despite abundant basal resources, leading to a 41%–66% reduction in estimated invertebrate production. We speculate that the functional response of our streams to agricultural land use (i.e., a modest increase in GPP but large declines in invertebrate production and shredder‐mediated litter decomposition rates) could be common across the afrotropics due to low fertiliser usage in this region and/or features of the local fauna. Although our study focuses a small number of streams, the large effect sizes that we report suggest that afrotropical streams could be strongly affected by rapid land use changes in the region, highlighting the need for additional research, monitoring, and conservation efforts in this poorly studied area of the world that is under increasing human pressures.

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Section: Discussionmentioning

confidence: 99%

Ecosystem structure and function of afrotropical streams with contrasting land use

et al. 2018

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“…; Iñiguez‐Armijos et al. ). Similarly to other montane freshwater (Taylor and Chauvet ; Astudillo et al.…”

Section: Introductionmentioning

confidence: 99%

Shifts in leaf litter breakdown along a forest–pasture–urban gradient in Andean streams

Iñiguez–Armijos

Rausche

Cueva

et al. 2016

Ecology and Evolution

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Tropical montane ecosystems of the Andes are critically threatened by a rapid land‐use change which can potentially affect stream variables, aquatic communities, and ecosystem processes such as leaf litter breakdown. However, these effects have not been sufficiently investigated in the Andean region and at high altitude locations in general. Here, we studied the influence of land use (forest–pasture–urban) on stream physico‐chemical variables (e.g., water temperature, nutrient concentration, and pH), aquatic communities (macroinvertebrates and aquatic fungi) and leaf litter breakdown rates in Andean streams (southern Ecuador), and how variation in those stream physico‐chemical variables affect macroinvertebrates and fungi related to leaf litter breakdown. We found that pH, water temperature, and nutrient concentration increased along the land‐use gradient. Macroinvertebrate communities were significantly different between land uses. Shredder richness and abundance were lower in pasture than forest sites and totally absent in urban sites, and fungal richness and biomass were higher in forest sites than in pasture and urban sites. Leaf litter breakdown rates became slower as riparian land use changed from natural to anthropogenically disturbed conditions and were largely determined by pH, water temperature, phosphate concentration, fungal activity, and single species of leaf‐shredding invertebrates. Our findings provide evidence that leaf litter breakdown in Andean streams is sensitive to riparian land‐use change, with urban streams being the most affected. In addition, this study highlights the role of fungal biomass and shredder species (Phylloicus; Trichoptera and Anchytarsus; Coleoptera) on leaf litter breakdown in Andean streams and the contribution of aquatic fungi in supporting this ecosystem process when shredders are absent or present low abundance in streams affected by urbanization. Finally, we summarize important implications in terms of managing of native vegetation and riparian buffers to promote ecological integrity and functioning of tropical Andean stream ecosystems.

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“…The results also illustrate an isolation and fragmentation of the natural vegetation around Lake Chala and Chemka Springs. In both cases the total native vegetation area was found to be below the recommended 70% for the maintenance of water quality [30]. The width of the Riparian buffer around Chemka springs is below the recommended thresholds for aquatic wildlife protection (30 m), and is at the lower limit of the thresholds for stream temperature stabilization (10 m), nutrient retention (15 m), sediment control (10 m), and pesticide retention (15 m) [80].…”

Section: Discussionmentioning

confidence: 88%

“…Fragstats 4.1 was used to calculate patch and class level statistics [74]. Evidence suggests that reporting solely the total area of natural vegetation in a catchment is insufficient and that the spatial configuration and quality of the patches of natural vegetation are also important considerations [30,[75][76][77]. At the patch level, we analyzed the distribution of the number of natural vegetation fragments for each period as a proxy for measuring landscape composition and configuration.…”

Section: Fragmentation Analysismentioning

confidence: 99%

Land Cover, Land Use, and Climate Change Impacts on Endemic Cichlid Habitats in Northern Tanzania

Kalácska

Arroyo‐Mora

Lucanus³

et al. 2017

Remote Sensing

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Abstract:Freshwater ecosystems are among the most threatened on Earth, facing environmental and anthropogenic pressures often surpassing their terrestrial counterparts. Land use and land cover change (LUCC) such as degradation and fragmentation of the terrestrial landscape negatively impacts aquatic ecosystems. Satellite imagery allows for an impartial assessment of the past to determine habitat alterations. It can also be used as a forecasting tool in the development of species conservation strategies through models based on ecological factors extracted from imagery.In this study, we analyze Landsat time sequences to quantify LUCC around three freshwater ecosystems with endemic cichlids in Tanzania. In addition, we examine population growth, agricultural expansion, and climate change as stressors that impact the habitats. We found that the natural vegetation cover surrounding Lake Chala decreased from 15.5% (1984) to 3.5% (2015). At Chemka Springs, we observed a decrease from 7.4% to 3.5% over the same period. While Lake Natron had minimal LUCC, severe climate change impacts have been forecasted for the region. Subsurface water data from the Gravity Recovery and Climate Experiment (GRACE) satellite observations further show a decrease in water resources for the study areas, which could be exacerbated by increased need from a growing population and an increase in agricultural land use.

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Deforestation and Benthic Indicators: How Much Vegetation Cover Is Needed to Sustain Healthy Andean Streams?

Cited by 56 publications

References 54 publications

Ecosystem structure and function of afrotropical streams with contrasting land use

Ecosystem structure and function of afrotropical streams with contrasting land use

Shifts in leaf litter breakdown along a forest–pasture–urban gradient in Andean streams

Land Cover, Land Use, and Climate Change Impacts on Endemic Cichlid Habitats in Northern Tanzania

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